This means that there now is a distinctive type of thinking marked off from mere discussion and reflection. It may be called either reasoning or proof. It is reasoning when we think of the regularity of the method for getting at and employing the unquestioned grounds which give validity to other statements. It is proof as regards the degree of logical desert thereby measured out to such propositions. Proof is the acceptance or rejection justified through the reasoning. To quote from Mill: "To give credence to a proposition as a conclusion from something else is to reason in the most extensive sense of the term. We say of a fact or statement, it is proved, when we believe its truth by reason of some other fact or statement from which it is said to follow."[47] Reasoning is marshaling a series of terms and propositions until we can bind some doubtful fact firmly to an unquestioned, although remote, truth; it is the regular way in which a certain proposition is brought to bear on a precarious one, clothing the latter with something of the peremptory quality of the former. So far as we reach this result, and so far as we can exhibit each step in the nexus and be sure it has been rightly performed, we have proof. But questions still face us. How about that truth upon which we fall back as guaranteeing the credibility of other statements--how about our major premise? Whence does it derive its guaranty? _Quis custodes custodiet?_ We may, of course, in turn subsume it under some further major premise, but an infinite regress is impossible, and on this track we are finally left hanging in the air. For _practical_ purposes the unquestioned principle may be taken as signifying mutual concession or agreement--it denotes that as a matter of fact its truth is not called in question by the parties concerned. This does admirably for settling arguments and controversies. It is a good way of amicably arranging matters among those already friends and fellow-citizens. But scientifically the widespread acceptance of an idea seems to testify to custom rather than to truth; prejudice is strengthened in influence, but hardly in value, by the number who share it; conceit is none the less self-conceit because it turns the heads of many. Great interest was indeed afterward taken in the range of persons who hold truths in common. The _quod semper ubique omnibus_ became of great importance. This, however, was not, in theory at least, because common agreement was supposed to constitute the major premise, but because it afforded confirmatory evidence of its self-evident and universal character.